Tubular rocker shaft with multiple internal compartments

ABSTRACT

A rocker shaft having at least two transversely formed interior compartments is provided each of which is devised for, and capable of, containing fluid at differing pressures. A multiplicity of generally radially directed holes present along the length of the rocker shaft communicate hydraulic fluid to the compartments via passageways present in the rocker arms, or valve deactivating rocker arm sections mounted thereon. Plugs installed within the rocker shaft at locations on either side of the holes provide compartmented regions within the shaft, each region of which has the capacity to contain hydraulic fluid at different pressures. The rocker shaft is capped at each end. Hydraulic fluid may be provided to the rocker shaft interior in a number of ways, such as through additional holes aligned with passageways provided in the cylinder head or through clearance openings between rocker shaft fasteners and rocker shaft mounting holes.

FIELD OF THE INVENTION

The present invention relates to a generally tubular rocker shaft, the interior of which is partitioned transversely into at least two regions or compartments to contain hydraulic fluid, usually engine oil with each of the partitioned compartments devised to contain fluid at different pressures. For engine applications where more than two compartments are required, plugs may be installed within the shaft to create additional compartments. Each end of the rocker shaft is closed or capped to provide a multiplicity of separate regions within the tubular shaft, each region of which is capable withstanding a different hydraulic pressure.

BACKGROUND OF THE INVENTION

In known prior art rocker shaft constructions containing more than one interior compartment, the interior of the rocker shaft tubular bore is longitudinally partitioned. Configurations of this kind are difficult to manufacture because of the requirement that two or more small diameter holes extending from end to end must be drilled into the rocker shaft as descriped for example in U.S. Pat. No. 5,592,907. Alternatively, a second tube or divider must be installed within the rocker shaft for example, as described in U.S. Pat. No. 6,598,578. With reference to the latter patent, apparently a rather complex manufacturing method is required wherein a kidney-shaped tube is slideably installed into the rocker shaft bore and the assembly is drawn through a mandrel to deform the rocker shaft around the kidney-shaped tube, mechanically closing the clearance between the rocker shaft bore and the kidney-shaped tube to form two separate longitudinal oil passages. Oil communication holes are then made through the rocker shaft and the internal kidney-shaped tube, contaminating the interior of the rocker shaft and the tube with particulates from the hole making process. Another disadvantage of this structure is that it cannot be used when valve deactivating rocker arms of two different cylinders are mounted on a rocker shaft assembly, especially wherein one passageway is used for lubricating oil and the other passageway for hydraulic fluid to engage or disengage the deactivating mechanism. Dependant upon an engine's firing order and the engine operating stratagem used to provide acceptable noise, vibration, and harshness (NVH), exhaust emissions, and other engine operating parameters, valve deactivating rocker arms on the same rocker shaft must be able to be separately engaged or disengaged. A transversely compartmented rocker shaft arrangement that overcomes such disadvantages, as provided by the present invention, is clearly desirable.

SUMMARY OF THE INVENTION

According to the invention a generally hollow rocker shaft is provided with an interior that is transversely partitioned into at least two longitudinal regions to contain hydraulic fluid, usually engine oil, with provisions to contain the fluid at different pressures within each of the regions. Plugs may be installed within the shaft at suitably spaced locations to create more than two compartments. The ends of the rocker shaft are closed as by capping to provide a multiplicity of separate compartmented regions within the shaft; each of these regions is capable of supporting a different hydraulic pressure. The compartment forming partitions or plugs are located and supported during the installation by means of a temporary dowel inserted through generally radially directed holes through the rocker shaft wall(s). The partitions or plugs may be configured so as to reduce the volume within some or all of the partitioned regions and such as to locate the sealing portion of the plug away from the radially formed holes in the rocker shaft wall(s).

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a perspective view of a cylinder head assembly incorporating a valve train assembly that includes rocker shafts of the kind contemplated by the invention.

FIG. 2 is a perspective view of an assembly of the tubular rocker shaft assembly of the invention in conjunction with an arrangement of standard and valve deactivating rocker arm components.

FIG. 3 is an end view of the rocker shaft assembly of FIG. 2.

FIG. 4 is a longitudinal sectional view taken along line 4-4 of FIG. 3 of the rocker shaft of the invention illustrating in detail the interior of the rocker shaft, the compartment forming plugs, and the passageways for hydraulic fluid.

FIG. 5 is an enlarged fragmented sectional view within circle 5 of FIG. 4 illustrating in detail the compartment forming plugs and the passages for hydraulic fluid.

DETAILED DESCRIPTION OF THE INVENTION

Engines that employ cylinder deactivation to conserve fuel typically do so by deactivating the individual valves of the cylinders. This invention describes a rocker shaft assembly for a cylinder deactivating engine equipped with an overhead valve train which incorporates center pivoting rockers arms mounted on said rocker shaft.

A number of the rocker arms are configured to deactivate valves. These valve deactivating rocker arms comprise valve actuation and cam follower sections linked together by a hydraulically actuated locking pin. In valve train mechanisms which utilize deactivating rocker arms for different cylinders on a common rocker shaft, it is typically necessary to selectively deactivate or re-activate these rocker arms in synchronization with the engine cylinder firing order by changing the pressure of the hydraulic fluid supplied to individual rocker arms to control the motion of the locking pin. The present invention provides the means to compartmentalize the rocker shaft interior so as to isolate the pressure supplied to one rocker arm from others. Means are also provided by the invention to isolate the pressure supplied to one section of a valve deactivating rocker arm from another section.

Referring to the drawing, FIG. 1 depicts the left cylinder head assembly 10 of a V8 engine which is configured to deactivate the middle two cylinders of that engine bank. Bolts 46 and 50 secure the intake rocker shaft assembly 38 and exhaust rocker shaft assembly 42 to the cylinder head subassembly 14. Each rocker shaft assembly includes two each standard rocker arms 30 and valve deactivating rocker arms 34 which are actuated by the camshaft 18. The rocker arm oil manifold assembly 22 is fastened to the rocker shafts 38 and 42 by bolts 46. The rocker arm oil manifold assembly 22 selectively provides high or low pressure hydraulic fluid, usually engine oil, to the valve deactivating rocker arms 34 by means of internal passageways (not shown) utilizing electrically actuated solenoid valves 26 to selectively engage or disengage the conventional locking mechanisms (not shown) of the valve deactivating rocker arms 34.

Shown in FIG. 2 is an intake rocker shaft assembly 38 illustrating the arrangement of standard rocker arms 30 and valve deactivating rocker arms 34 on the rocker shaft subassembly 54 and an arrangement of generally radially directed through holes 118, 146, 148, and 150 through said shaft.

FIG. 3 depicts an end view of the intake rocker shaft assembly 38 illustrating the relationship of the rocker shaft subassembly 54 and a conventional rocker arm 30 and valve deactivating rocker arm 34 with line 4-4 referencing the sectional view shown in FIG. 4.

FIG. 4 illustrates the longitudinal section of the intake rocker shaft assembly 38 of the invention, a cross section of which is shown in FIG. 3. Shown in FIG. 4 are the generally radially directed through holes 118, 146, 148, and 150 through which bolts 46 and 50 (FIG. 1) are installed. The arrangement of standard rocker arms 30 and valve deactivating rocker arms 34 on the rocker shaft subassembly 54 is shown relative to the plugs 62, 74, and 78 installed in the shaft 58 which in turn are used to create regions 66 and 68 as well as bolt through hole space 70 within said shaft. In the preferred embodiment shown here, the regions 68 are disposed so as to provide lubricating oil to the standard rocker arms 30 through generally radially directed holes 112 and 116 (FIG. 4) through the shaft 58. The region 66 is a passageway for the supply of pressurized engine oil from the cylinder head 14 (FIG. 1) to the rocker arm oil manifold assembly 22 (FIG. 1) through the clearance between the generally radially directed holes 146 and the bolts 46 (FIG. 1). Hydraulic fluid at selectively high or low pressure according to the disposition of control valves 26 (FIG. 1) is communicated through internal passageways (not shown) within the rocker arm oil manifold assembly 22 (FIG. 1) through the clearance between the generally radially directed holes 118 and the bolts 46 (FIG. 1). Pressurized engine oil is similarly communicated through internal passageways (now shown) within the rocker arm oil manifold assembly 22 (FIG. 1) through the clearances between the generally radially directed holes 148 and the bolts 46 (FIG. 1) to the regions 68 within the shaft 58. it is apparent that fluid may be provided to the rocker shaft interior in a number of ways, such as through additional holes aligned with passageways provided in the cylinder head or through clearance openings between rocker shaft fasteners and rocker shaft mounting holes.

FIG. 5 illustrates the plugs 78 and 74 that are sequentially installed from one end of the shaft 58. The plug 78 is a generally hollow, tubular member having a distal open end 106 and a proximal open end 98 and an interior bore 102. The plug 78 is sized to slideably fit within the bore of the shaft 58. The ball 82 is sized such that it provides an interference fit by expanding the interior 102 of the plug 78 or the interior bore 90 of the insert 78. During assembly of the rocker shaft subassembly 54, plug 78 is inserted into the shaft 58 and the open end 106 is abutted against a dowel pin (not shown) temporarily inserted through the generally radially directed holes 146. The dowel pin locates plug 78 as the ball 82 is pushed into the open end 98 of the plug 78 into interior bore 102, locally deflecting the plug 78 such that it's outer diameter provides an interference fit with the bore of the tube 58, retaining the plug 78 within the shaft 58 and sealing the bore of shaft 58, thereby creating regions 70 and 66. In the preferred embodiment plug 74 is a generally cup shaped or tubular insert having a distal closed end 94 and a proximal open end 86 and an interior bore 90. The plug is sized so as to seal and minimize the compartment volume of hydraulic fluid contained within region 70 so as to improve hydraulic performance. Plug 74 is installed after plug 78 has been installed and is installed in a similar manner.

The above described advantages of the transversely compartmented rocker shaft of the invention are not meant to limit the scope of the invention. Although the invention has been described with respect to preferred embodiments, many variations and modifications will become apparent to those skilled in the art. It is therefore intended that the claims be interpreted as broadly as possible in view of the prior art, to include all such variations and modifications. 

1. A longitudinal rocker shaft having a generally hollow interior with plugged ends and containing at least two transverse isolated fluid confining compartments formed by intermittently plugging the interior of the shaft with plugs inserted and secured at locations within the shaft to provide the desired predetermined compartment size.
 2. The rocker shaft of claim 1 comprising a tubular member.
 3. The rocker shaft of claim 1 configured such that hydraulic fluid is introduced to at least one of said compartments through holes provided by a cylinder head.
 4. The rocker shaft of claim 1 wherein fluid is introduced to the rocker shaft compartments through clearance openings between rocker shaft fasteners and rocker shaft mounting holes.
 5. The rocker shaft of claim 1 wherein said compartments are formed by tubular plugs slideably inserted within the rocker shaft bore.
 6. The rocker shaft of claim 1 wherein said compartments are formed by an insert having a distal closed end.
 7. The rocker shaft of claim 5 wherein said tubular plugs are secured in place by an interference fit insert introduced into said tubular plugs.
 8. The rocker shaft of claim 7 wherein the insert comprises a ball.
 9. The rocker shaft of claim 1 provided with passageways for introducing fluid to said compartments through holes that are aligned with passageways of an associated cylinder head.
 10. The rocker shaft of claim 1 provided with passageways for introducing fluid to said compartments through clearance openings between rocker shaft fasteners and rocker shaft mounting holes.
 11. The rocker shaft of claim 1 wherein the inserted plugs are sized so as to seal and minimize the compartment volume. 